Recently, an attempt was made to evaluate the antipruritic effect of an analgesic drug. Some of the problems encountered will be discussed, and a blueprint for the proper clinical investigation of antipruritic drugs will be presented.
Experimental Procedure
In previous animal experiments, the drug was found to depress the perception of cutaneous stimuli. In addition, it was found to have potent local anesthetic activity, mild antihistaminic action, and potentiation of analgesia.
The case material consisted of patients with severe chronic pruritus. In a pilot study on 23 patients, the drug showed considerable promise, and a subsequently administered placebo was ineffective. The experiment was then continued with 79 additional cases, with use of a carefully planned, double-blind, randomized technique. Statistical analysis of the complete data demonstrated that the test drug was not superior to the placebo. Appreciation of the difficulties and pitfalls inherent in the study led to a